A well usually consists of a casing cemented to the formation and one or more injection or production tubes within the casing. Occasionally, an open bore hole, i.e., one without a casing, contains the injection or production tubing strings therein. The well may often penetrate numerous production or injection zones of interest. These production or injection zones must be isolated from each other and from the casing as a whole so that hydrocarbons or injected fluids and gases can be placed in a particular zone of interest. The zones of interest are isolated by what is known in the industry as packers.
Packers normally are placed above and below the zone of interest and seal the production and/or injection tubing within the casing or wellbore. Packers can either be permanent or retrievable depending upon the operation.
Many parts of the Unites States and other areas of the world have hydrocarbons which are too heavy to be produced and flow on their own without assistance. To assist the movement of the hydrocarbons, steam, non-condensible gas or other injectible fluids and gas combinations are often injected into the formation to assist the movement of hydrocarbons. In areas where there are multiple production zones and each zone requires a different steam quality and/or injectible fluid, these zones must be isolated by packers so that the correct steam quality and/or injectible fluid or gas can be injected into the specific zone of interest. For example, two adjacent producing zones may require a steam quality of 80% in the first zone but only a steam quality of 50% in the second zone or both zones may require the same quality steam but they are separated by a fixed non-producing zone which must be packed off to avoid wasting the injected steam.
Steam injection with its high temperatures presents additional problems. In addition, the movement of the tubing string within the wellbore may damage the packer. Also, the packer may not be able to hold pressure within the packed off zone immediately after placement because it may not have adequately engaged the sides of the tubing string or wellbore.
Thus, it would be highly desirable to have a packer suitable for use in high-temperature environments which are not damaged by movement of the tubing string within the wellbore or casing. It is also desirable to have a packer firmly engage the wellbore or casing after insertion therein.